In 1983, BMW sprang a surprise on everyone in the second 5 Series E28 generation when the BMW 524td was powered by the first BMW diesel engine. In 1986, BMW supplemented this model powered by a turbocharged engine in the form of the 524d with a six-cylinder naturally aspirated diesel engine. This model was particularly fuel efficient. However, this economical approach was at the cost of the driving pleasure so typical of BMW so that only 4,239 purchasers opted to buy the 524d over a period of 15 months.